We can often measure the magnitude of an event by our ability to recall the moment in which we heard about it.

And if you’ve been a San Diegan for any length of time – if you cheered the many hundreds of his big hits on the football field or got a Say Ow tattoo in your McDonald’s Happy Meal or had him ever call you “buddy” – you remember where you were when you heard Junior Seau had committed suicide.

I was on the sand at Mission Beach watching Donovan McNabb and E.J. Manuel work out with quarterback coach George Whitfield the morning of May 2, 2012. I got the text and after confirming it was true passed the message to Whitfield, who relayed it to McNabb, who let out an extended, “Noooo.”

Junior Seau: 20 years of greatness

We asked 20 people who knew the Chargers great for their one-of-a-kind memories, to highlight some of Junior’s finest moments and his impact on the NFL. Each of them recalled one of Seau's 20 NFL seasons.

It was a guttural sound that lingers still in my mind, summing up as it did the reaction of a county and even a country.

And in the one year since, as we’ve come to know more than we ever wanted to about what lurked beneath the veneer of a legend, it still seems unreal.

Moreover, the feeling of emptiness remains, and the questions of why linger even as some answers have seemingly been provided.

Seau’s legacy remains an evolution.

There is no questioning all he did while alive, and his unrivaled 20 years in the NFL are merely the backdrop of that lasting impression.

“He had a huge impact, and it still resonates here in this town,” Tony Gwynn, perhaps Seau’s only rival in terms of being a cherished local legend, said in an interview that is part of a tribute to Seau airing at 8 p.m. tonight on U-T TV. “… He set a really good example of how you’re supposed to go about your work – you go hard each day, you try to affect change not only in the game of football but affect change in life. It rubbed off on a whole lot of people, including me.”

Yet how Seau is and should be remembered has become a complicated matter.

The man who made so many so happy was so troubled.

All that Seau was known to be before his death – former Charger, future Hall of Famer, surfer, local icon, generous to a fault – has been conjoined with some other disturbing descriptions.

Depressed. Angry. Addicted.

“His enthusiasm for life is one that’s challenging for us as we look at Junior’s legacy to an extent,” said longtime Padres closer Trevor Hoffman, who spent time with Seau at charitable events over the years. “He really impacted the people around him to cherish every single moment … But it might be difficult to hear that when we say enthusiasm for life.”

Indeed. The legacy of Seau’s life is difficult to rectify.

But his death was not entirely an ending.

Whatever pall clouds our memory of Seau, the impact his death had might be even greater than his life did.

Seau was not the first former NFL player to commit suicide, nor the first to be diagnosed after death with a degenerative brain disease that is the result of brain trauma.

But he was the biggest name.

Mary Ann Easterling’s husband, Ray, played eight years in the NFL and struggled through his final two decades with the very same symptoms Seau exhibited. Ray Easterling committed suicide 13 days before Seau.

Asked Tuesday what has changed in the wake of Seau killing himself, Easterling said, “The awareness has certainly been out there.”

She spoke also to something that makes all this talk about concussions so much bigger than the fate of the NFL.

“I’ve seen a lot more parents taking responsibility,” Easterling said. “I think that’s where the impact is going to be – that this has long-term effects on health and they need to take care of themselves.”

The Easterlings were among the original plaintiffs in the class action lawsuit filed in 2011. Junior Seau’s family and some 4,000-plus other former NFL players and their families are now party to that suit, which alleges the NFL suppressed information about the long-term dangers of concussions.

The NFL, for its part, has for a few years been taking measures to limit head collisions. And its rules changes in the past year appear set to diminish those contacts even more drastically.

Those measures may have been taken were Seau still alive.

But his death was impossible to ignore and has, without question, spurred discussion.

“The guys who committed suicide, some of whom we found out had CTE, there wasn’t anything done,” said Gary Plummer, Seau’s former teammate and longtime friend. “Junior being such a high-profile guy, it truly pushed the NFL into action, and that should be his legacy. And he should be proud of that fact, because he was too good of a human being to die in vain.”